Some conventional systems for tracking and/or monitoring assets (herein generally referred to as “asset tracking systems”) utilize wireless tags that generally respond to any broadcast that is made. The wireless tags usually are passive, and the responses that the passive wireless tags make are often referred to as “chirps.”
More sophisticated conventional asset tracking systems utilize semi-passive wireless tags and/or active wireless tags. A semi-passive wireless tag includes an internal power source for transmitting, and an active wireless tag includes an internal power source for both receiving and transmitting. Semi-passive and active wireless tags generally have greater capabilities than passive wireless tags due to the internal power sources. Of course, power consumption is always a concern when a wireless tag includes an internal power source, since the internal power supply limits the useful life of the wireless tag, after which time maintenance is required (e.g., replacement of the internal power source).
In improved asset tracking systems, such as disclosed in U.S. Pat. No. 6,934,540 and other of the above-incorporated patent applications and patents, a wireless tag responds to a broadcast if the broadcast includes a common designation matching a common designation of the wireless tag. Such a common designation may comprise, for example, an “asset class” associated with the wireless tag. Ad hoc networks further may be created based on such classes, which ad hoc networks are referred to as “class based” networks.
Class based networks (and common designation networks in general) are beneficial because, in such networks, a communication device, such as a wireless tag, generally only transmits a response to a broadcast if the broadcast includes a class (or common designation) that matches a class (or common designation) of that communication device. Indeed, in a communication device employing a wakeup sequence of one or more of the patent references incorporated herein by reference, such communication device does not even process a broadcast once it is determined that the broadcast fails to include a matching class of the communication device. Consequently, the internal power supply of a semi-passive or active communication device is not drained by needless processing and/or responses to broadcasts.
The present invention generally relates to wireless ad-hoc networks. A need exists for improvement in wireless network apparatus, systems, and methods. These, and other needs, are addressed by one or more aspects of the present invention.